What is the particle X? a) alpha b) beta c) proton d) neutron

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Byron Ellis
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2 16. Radioactive carbon-14 is produced in the upper atmosphere by the reaction 14 7N + X > 14 6C + 1 1H What is the particle X? a) alpha b) beta c) proton d) neutron 17. Carbon-13 is stable, carbon-14 is radioactive. What type of radioactive decay is carbon-14 expected to undergo? a) alpha b) beta c) positron d) electron capture 18. In the nuclear transmutation, 16 8O (p, ) X, what is the product nucleus X? a) oxygen-16 b) oxygen15 c) nitrogen-13 d) nitrogen What order process is radioactive decay? a) zero order b) first order c) second order d) third order 20. An ancient wooden artifact is believed to be 5000 years old. What percentage of the carbon-14 originally in the artifact would remain after this time? The half-life of carbon-14 is 5730 years. (Show calculation) 21. Carbon-11 has a half-life of 20.4 minutes. Assuming you start with a 500 g sample of carbon-11, how much will remain after 24 hours? (Show calculation) 22. The mass of the iron-56 nucleus is amu. What is the mass defect of this nucleus? (Show calculation)

3 23. The mass defect of the helium-4 nucleus is amu. What is the nuclear binding energy of this nucleus in J? a) 1.56 X b) 4.95 X c) 4.54 X d) 1.92 X In a nuclear power plant, a) a subcritical mass of uranium-235 is used. b) enough uranium-235 is used to maintain a chain reaction. c) small nuclei are fused together to form a larger nucleus. d) slow moving protons cause the fission of uranium The general formula of a cyclic alkene is a) CnH2n+2 b) CnH2n c) CnH2n-2 d) CnHn 26. Which is incorrect? a) ethane, C2H6 b) propane, C3H8 c) butane, C4H10 d) pentane, C5H Which is the carboxylic acid functional group? O O O O a) C H b) C OH c) C d) C NH2 28. Name the following compound: CHCH2CH2CHCH2CHCH2 CH2 a) 5,7-diethyl-2-methyloctane b) 4-ethyl-1,1,6-trimethyloctane c) 5-ethyl-2,7-dimethylnonane d) 5-ethyl-3,8-dimethylnonane 29. Draw the following molecule: trans-5-methyl-2-hexene 30. Draw the following molecule: 1-ethyl-1-methylcyclopentane

4 31. Which is the isopropyl group? a) CH2CH2 b) CH c) CH2 d) CH2CH2CH 32. Structural isomers have a) the same structure but different molecular formulas. b) their atoms connected in the same order. c) their atoms connected in a different order. d) different structures and different molecular formulas. 33. Draw and name the structural isomers which have the molecular formula C4H9Br.

5 Answers 1. A C 2. C B 3. B 14. A 25. C 4. C 15. A 26. D 5. A 16. D 27. B 6. A 17. B 28. C 7. A 18. C A 19. B D B 10. A C 11. B Cr2O7 2 (aq) + 6 Br (aq) + 14 H + (aq) 2 Cr 3+ (aq) + 3 Br2 (aq) + 7 H2O (l) 7. Oxidation Half-Reaction: Pb (s) Pb 2+ (aq) + 2 e E = V Reduction Half-Reaction: Cu 2+ (aq) + 2 e Cu (s) E = V _ Overall: Pb (s) + Cu 2+ (aq) Cu (s) + Pb 2+ (aq) E cell = V 8. ΔG = (2)(96485 J mol 1 K 1 )(+0.13 V) = J 25 kj 9. ΔG = (4)(96485 J mol 1 K 1 )(+0.46 V) = J J = (8.314 J mol 1 K 1 )( K)ln(Keq), Keq = e = 1.27 X (1.5 C/s)(45 min)(60 s/min) = 4050 C (4050 C)(1 mol e / C)(1 mol Cu / 2 mol e )( g Cu / mol Cu) = 1.3 g of Cu I 0 1e Xe O 15 7N e (positron emission) 15. X 4 2He Pb X = Po (polonium-210) 16. X = 1 0n (neutron) 17. Carbon-14 has too many neutrons (n/p ratio is too high for stability); -decay reduces the n/p ratio O + 1 1H 4 2He + X X = 13 7N (nitrogen-13) 20. k = ln(2) / t½ = X 10 4 yr 1 N0 = 100% Nt =? ln(nt) = ( X 10 4 yr 1 )(5000 yr) + ln(100%) Nt = 54.6% 54.6% of the original amount of carbon-14 remains. 21. k = ln(2) / t½ = ln(2) / 29.4 min = min 1, t = (24 hr)(60 min/hr) = 1440 min ln(nt) = kt + ln(no), ln(nt) = ( min 1 )(1440 min) + ln(500 g) ln(nt) = , Nt = e = 2.82 X g of carbon-11 remains

6 Another way to calculate Nt is, Nt = (½) n No where n = number of half-lives = t / t½ n = 1440 min / 20.4 min/half-life = half-lives No = 500 g. Therefore, Nt = (½) (500 g) = 2.82 X g of carbon-11 remains. 22. Mass of 26 protons = (26 p)( amu/p) = amu Mass of 30 neutrons = (30 n)( amu/n) = amu amu amu Mass defect = amu 23. ΔE = Δmc 2 = ( amu)(1 g / X amu)(1 kg / 1000 g)(2.998 X 10 8 m/s) 2 = 4.54 X J 29. H \ / C==C / \ H CH2 CH trans-5-methyl-2-hexens ethyl-1-methylcyclopentane 33. CH2 CH2 CH2 Br 1-bromobutane CH2 CH Br 2-bromobutane CH CH2 Br 1-bromo-2-methyl-propane C Br 2-bromo-2-methylpropane

CHEM 1412 Practice Exam 3, Chapters 18, 19 & 24 Chang

CHEM 1412 Practice Exam 3, Chapters 18, 19 & 24 Chang F = 96485 J/V mol = 96485 C/mol of e Ecell = E cell (0.0592/n) log(q) = E cell (0.0257/n) ln(q) G = n F E cell G = RT ln(keq) lnnt = kt + lnno Amp